Surface-waterproofing sheet for mineral board using a mixed-use nonwoven fabric and a waterproofing coating layer, and a production method therefor

ABSTRACT

The present invention relates to a surface-waterproof sheet for inorganic boards including multi-use non-woven fabrics and a waterproof coating layer, and a method of manufacturing the same. The method includes preparing a multi-use non-woven fabric composed of cellulose fibers, glass fibers and organic fibers; preparing a waterproof coating solution containing a powdery acrylic binder, water, an inorganic filler, a water repellent, a pigment and an antimicrobial agent; and coating the waterproof coating solution on the multi-use non-woven fabric, followed by drying the waterproof coating solution, thereby providing surface-waterproof sheet for inorganic boards for buildings, which has improved adhesion to the inorganic board and economic feasibility.

TECHNICAL FIELD

The present invention relates to a surface-waterproof sheet forinorganic boards including a multi-use non-woven fabric and a waterproofcoating layer and a method of manufacturing the same, and moreparticularly, to a technology of providing a surface-waterproof sheet,which include a single nonwoven fabric layer and a waterproof coatinglayer formed thereon to improve adhesion to an inorganic board whileensuring economic feasibility.

BACKGROUND ART

As a waterproof surface material for gypsum boards for buildings, a2-layer structure surface material has been generally used in the art.Here, the 2-layer structure refers to a structure including an outerlayer made of cellulose fibers and an inner core adhesive layer placedbeneath the outer layer. At this time, to provide waterproofingproperties to the 2-layer structure surface material, the entirety ofthe 2-layer structure surface material is generally impregnated into awaterproof binder composition. However, as the inner core adhesive layeris impregnated into the waterproof binder composition, adhesion to thegypsum board is lowered and dimensional stability and cuttingperformance are also lowered, thereby deteriorating the overallproperties of the surface material.

DISCLOSURE Technical Problem

An aspect of the present invention is to provide a surface-waterproofsheet for inorganic boards, in which a waterproof paper body to beadhered to an inorganic board is formed of a single layer of multi-usenon-woven fabrics composed of cellulose fibers, glass fibers and organicfibers, and is then coated with a waterproof coating solution includingbinder powder, water, an inorganic filler, a water repellent, a pigmentand an antimicrobial agent, thereby improving waterproof properties andadhesion to the inorganic board.

Another aspect of the present invention is to provide a method ofmanufacturing a surface-waterproof sheet for inorganic boards, which canimprove dimensional stability and cutting properties while securingstrength of the inorganic board by adjusting a pore size and a basisweight of multi-use non-woven fabrics, and the coating amount, viscosityand composition of a waterproof coating solution.

Technical Solution

In accordance with one aspect of the present invention, asurface-waterproof sheet for inorganic boards includes: a multi-usenon-woven fabric composed of cellulose fibers, glass fibers and organicfibers; and a waterproof coating layer coated on the multi-use non-wovenfabric.

The multi-use non-woven fabric may include 30˜70 wt % of the cellulosefibers, 28˜60 wt % of the glass fibers and 2˜20 wt % of the organicfibers.

The cellulose fibers may have an average diameter of 5 μm to 100 μm andan average length of 1 mm to 30 mm; and each of the glass fibers and theorganic fibers may have an average diameter of 5 μm to 20 μm and anaverage length of 1 mm to 30 mm

The multi-use non-woven fabric may be formed as a single layer of thenonwoven fabric having a basis weight of 30 g/m² to 100 g/m², and mayhave a thickness of 0.25 mm to 0.55 mm

The multi-use non-woven fabric may further include 0.1˜3 wt % of a drypaper strengthener or wet paper strengthener. The dry paper strengthenermay contain starch or polyacrylamide, and the wet paper strengthener maycontain at least one selected from among urea formaldehyde resins,melamine formaldehyde resins, polyamide resins, glyoxylatedpolyacrylamide resins, and polyethylene imine resins.

The waterproof coating layer may be formed using a waterproof coatingsolution that includes 3˜30 wt % of a powdery acrylic binder, 10˜50 wt %of water, 20˜70 wt % of an inorganic filler, 0.5˜10 wt % of a waterrepellent, 0.5˜5 wt % of a pigment, and 0.2˜5 wt % of an antimicrobialagent.

The waterproof coating solution may have a viscosity of 50˜500 cps.Here, the inorganic filler may include calcium carbonate (CaCO₃) havingan average particle size of 5 μm to 50 μm, and the water repellent mayinclude a fluorocarbon or wax type water repellent.

The waterproof coating layer may be permeated up to 5% to 80% of athickness of the non-woven fabric from an upper surface of the non-wovenfabric to a bottom thereof. Here, the non-woven fabric may have anaverage pore size of 10 μm to 100 μm in a region into which thewaterproof coating layer is not permeated, and an average pore size of 5μm to 50 μm in a region into which the waterproof coating layer ispermeated.

The surface-waterproof sheet may have a total thickness of 0.27 mm to0.57 mm The inorganic board may include at least one selected from amongmedium density fiberboard (MDF), plywood, cellulose fibers-reinforcedcement board, magnesium board, glued laminated timber, high-densityfiberboard, ceramic tile, porcelain tile, ceramic board, gypsum board,cement board, and MgO board.

In accordance with another aspect of the present invention, a method ofmanufacturing a surface-waterproof sheet for inorganic boards includes:(a) preparing a multi-use non-woven fabric by mixing cellulose fibers,glass fibers and organic fibers; (b) preparing a waterproof coatingsolution containing a powdery acrylic binder, water, an inorganicfiller, a water repellent, a pigment, and an antimicrobial agent; and(c) coating the waterproof coating solution on the multi-use non-wovenfabric, followed by drying the waterproof coating solution.

The coating of the waterproof coating solution may be performed by onemethod selected from among drum coating, roll coating, knife coating,spray coating, and comma coating; and the drying of the waterproofcoating solution may be performed at a temperature of 100° C. to 200° C.for 1 to 10 minutes.

Advantageous Effects

In the surface-waterproof sheet for inorganic boards according to thepresent invention, a waterproof paper body to be adhered to an inorganicboard is formed as a single layer of multi-use non-woven fabrics, and awaterproof coating solution is permeated up to 5% to 80% of a thicknessof the non-woven fabric layer from an upper surface of the non-wovenfabric layer to a bottom thereof, thereby providing better waterproofproperties than existing surface materials while improving adhesion tothe inorganic board.

Further, the method of manufacturing a surface-waterproof sheet forinorganic boards according to the present invention may improvedimensional stability and cutting properties while securing strength ofthe inorganic board by adjusting a pore size and a basis weight of themulti-use non-woven fabrics, and the coating amount, viscosity andcomposition of the waterproof coating solution.

DESCRIPTION OF DRAWING

FIG. 1 is a cross-section view of a surface-waterproof sheet forinorganic boards according to one embodiment of the present invention.

FIG. 2 is a flowchart of a method of manufacturing a surface-waterproofsheet for inorganic boards according to one embodiment of the presentinvention.

FIG. 3 is a diagram illustrating the method of manufacturing asurface-waterproof sheet for inorganic boards according to theembodiment of the present invention.

BEST MODE

Next, exemplary embodiments of the present invention will be describedin detail with reference to the accompanying drawings. The above andother aspects, features, and advantages of the present invention willbecome apparent from the detailed description of the followingembodiments in conjunction with the accompanying drawings. It should beunderstood that the present invention is not limited to the followingembodiments and may be embodied in different ways, and that theembodiments are given to provide complete disclosure and a thoroughunderstanding of the present invention to those skilled in the art. Thescope of the present invention is defined only by the claims. The samecomponents will be denoted by the same reference numerals throughout thespecification.

FIG. 1 is a cross-sectional view of a surface-waterproof sheet forinorganic boards according to one embodiment of the present invention.

First, referring to FIG. 1, a multi-use non-woven fabric 100 composed ofcellulose fibers, glass fibers and organic fibers is shown.

The multi-use non-woven fabric may include 30˜70 wt % of the cellulosefibers, 28˜60 wt % of the glass fibers and 2˜20 wt % of the organicfibers. Also, the cellulose fibers may have an average diameter of 5 μmto 100 μm, and an average length of 1 mm to 30 mm

Here, the cellulose fibers serve to adjust an average pore size of thenonwoven fabric. If the cellulose fibers are present in an amount ofless than 30 wt % or most cellulose fibers have an average size belowthe aforementioned range, the pore size of the nonwoven fabric becomestoo large, causing deterioration of waterproof properties.

If the cellulose fibers are present in an amount of more than 70 wt % orhave an average size above the aforementioned range, the amount of glassfibers or organic fibers becomes excessively increased, causingreduction in tensile strength of the multi-use non-woven fabric.

Also, each of the glass fibers and the organic fibers may have anaverage diameter of 5 μm to 20 μm and an average length of 1 mm to 30 mmThe glass fibers are present in an amount of 28 wt % to 60 wt % and theorganic fibers are present in an amount of 2 wt % to 20 wt %.

Here, the glass fibers serve to secure strength and waterproofproperties of the multi-use non-woven fabric and thus secure dimensionalstability. If the glass fibers are present in an amount of less than 28wt % or have an average size below the aforementioned range, thenon-woven fabric has low strength. If the glass fibers are present in anamount of more than 60 wt %, the pore size of the non-woven fabric isexcessively increased, thereby causing deterioration in waterproofproperties.

Further, the organic fibers serve to keep certain waterproof propertiesand folding strength while providing flexibility to the non-wovenfabric. If the organic fibers are present in an amount of less than 2 wt% or have an average size below the aforementioned range, theflexibility of the multi-use non-woven fabric can be deteriorated. Ifthe organic fibers are present in an amount of more than 20 wt %, thepore size of the non-woven fabric is excessively increased, therebycausing deterioration in waterproof properties and strength of thenon-woven fabric. Next, the multi-use non-woven fabric 100 furtherincludes 0.1˜3 wt % of a dry paper strengthener or wet paperstrengthener. The dry paper strengthener includes starch orpolyacrylamide, and the wet paper strengthener includes at least oneselected from among urea formaldehyde resins, melamine formaldehyderesins, polyamide resins, glyoxylated polyacrylamide resins, andpolyethylene imine resins. The dry paper strengthener or the wet paperstrengthener may be optionally added in accordance with the use ofinorganic boards.

The raw materials for the multi-use non-woven fabric are formed to athickness of 0.25 mm to 0.55 mm Further, the multi-use non-woven fabricmay be formed as a single non-woven fabric layer having a basis weightof 30 g/m² to 100 g/m². Herein, the term “thickness of the multi-usenon-woven fabric” substantially refers to the sum of the thickness ofthe non-woven fabric 100 and the thickness of a waterproof coatingsolution permeation layer 110, as shown in FIG. 1. If the thickness ofthe multi-use non-woven fabric is less than 0.25 mm, the waterproofsheet cannot function as desired. If the thickness of the multi-usenon-woven fabric is more than 0.55 mm, air-permeability required of thewaterproof sheet can be deteriorated.

In addition, performance of the waterproof sheet can be deteriorated ifthe basis weight of the non-woven fabric is less than 30 g/m², and theair-permeability can be deteriorated if the basis weight of thenon-woven fabric exceeds 100 g/m².

The waterproof sheet according to the present invention includes awaterproof coating layer 120 on the multi-use non-woven fabric.

Here, the waterproof coating layer 120 is formed of a waterproof coatingsolution which contains 3˜30 wt % of a powdery acrylic binder, 10˜50 wt% of water, 20˜70 wt % of an inorganic filler, 0.5˜10 wt % of a waterrepellent, 0.5˜5 wt % of a pigment, and 0.2˜5 wt % of an antimicrobialagent.

The inorganic filler may be calcium carbonate (CaCO₃) having an averageparticle size of 5 μm to 50 μm, and the water repellent may be afluorocarbon or wax type water repellent.

Here, the waterproof coating solution may have a viscosity of 50˜500cps. If the viscosity of the waterproof coating solution is lower than50 cps, the amount of the coating solution permeated into the multi-usenon-woven fabric decreases, causing the waterproof coating layer 120 tobe easily separated. If the viscosity is higher than 500 cps, the amountof the coating solution permeated into the multi-use non-woven fabricexcessively increases, causing deterioration in adhesion to theinorganic board.

Accordingly, the waterproof coating solution may have a viscosityranging from 30 g/m² to 200 g/m². At this time, the waterproof coatinglayer 120 may have a coating structure that is permeated up to 5% to 80%of the thickness of the non-woven fabric from an upper surface of thenon-woven fabric to a bottom thereof.

Further, like the effect of the viscosity, if the coating amount and thepermeation thickness of the waterproof coating solution are less thanthe respective lower limits, the coating layer can be easily peeled off.If the coating amount and the permeation thickness of the waterproofcoating solution exceed the upper limits, adhesion of the waterproofsheet can be deteriorated.

In the present embodiment, the surface-waterproof sheet for inorganicboards is formed by coating one layer of the multi-use non-woven fabric100+110 with the waterproof coating layer 110+120. At this time, thenon-woven fabric has an average pore size of 10 μm to 100 μm in a region100 into which the waterproof coating layer 120 is not permeated, and anaverage pore size of 5 μm to 50 μm in a region 110 into which thewaterproof coating layer 120 is permeated. Here, a pore size of thenon-woven fabric smaller than the lower limit can cause difficulty inmanufacture of the waterproof sheet and deterioration ofair-permeability of the waterproof sheet, and a pore size of thenon-woven fabric higher than the upper limit can cause deterioration ofwaterproof properties.

Also, the surface-waterproof sheet including the waterproof coatinglayer may have a total thickness of 0.27 mm to 0.57 mm Here, if thetotal thickness of the surface-waterproof sheet is less than 0.27 mm,waterproofing properties can be deteriorated, and if the total thicknessof the surface-waterproof sheet is greater than 0.57 mm, airpermeability can be deteriorated. In such cases, the properties of thesurface-waterproof sheet to be adhered to an inorganic board can bedeteriorated.

At this time, the inorganic board may include at least one selected fromamong medium density fiberboard (MDF), plywood, cellulosefiber-reinforced cement board, magnesium board, glued laminated timber,high density fiberboard, ceramic tile, porcelain tile, ceramic board,gypsum board, cement board, and MgO board.

The waterproofing properties and air permeability will be describedbelow in more detail with reference to examples.

Next, a method of manufacturing a surface-waterproof sheet according tothe present invention will be described.

FIG. 2 is a flowchart of a method of manufacturing a surface-waterproofsheet for inorganic boards according to one embodiment of the presentinvention.

Referring to FIG. 2, the method includes preparing a multi-use non-wovenfabric by mixing cellulose fibers, glass fibers and organic fibers(S100); preparing a waterproof coating solution containing a powderyacrylic binder, water, an inorganic filler, a water repellent, apigment, and an antimicrobial agent (S110); and coating the waterproofcoating solution on the multi-use non-woven fabric, followed by dryingthe waterproof coating solution (S120).

Here, although operation of preparing a multi-use non-woven fabric(S100) and operation of preparing a waterproof coating solution (S110)are shown in sequence, these operations can be performed independently,and thus the present invention is not limited thereto.

Further, the compositions or contents of the multi-use non-woven fabricand the waterproof coating solution are the same as those describedabove with reference to FIG. 1.

Next, operation of coating the waterproof coating solution is performedby one process selected from among drum coating, roll coating, knifecoating, spray coating, and comma coating. Further, drying is performedat a temperature of 100° C. to 200° C. for 1 to 10 minutes. Here, if thedrying temperature is lower than 100° C. or the drying time is shorterthan 1 minute, the waterproof coating layer is not normally formed. Onthe other hand, if the drying temperature is higher than 200° C. or thedrying time is longer than 10 minutes, the waterproof coating layer canbe damaged, thereby deteriorating the waterproofing properties.

FIG. 3 is a schematic diagram of the method of manufacturing thesurface-waterproof sheet for inorganic boards according to theembodiment of the present invention, which shows a drum coating process.

Referring to FIG. 3, a coating drum 220 is used for successivelyuncoiling a multi-use non-woven fabric 210 on a multi-use non-wovenfabric roll 200. Here, the coating drum 220 is configured to completelyblock one side of the non-woven fabric 210 such that a waterproofcoating solution 230 can be applied only to the one side of thenon-woven fabric 210 in a coating container 240 filled with thewaterproof coating solution 230.

Through this procedure, the waterproof coating solution 230 is permeatedup to 5% to 80% of the thickness of the non-woven fabric 210 from anupper surface of the non-woven fabric 210 to a bottom thereof, and aregion of the non-woven fabric 210 under this range is maintainedwithout being permeated by the waterproof coating solution, therebymaintaining adhesion to the inorganic board.

Next, a knife 245 is placed above the non-woven fabric 210 and is usedto adjust the thickness of the waterproof coating layer by removing thewaterproof coating solution 230, which comes out of the coating drum 220in a coated state on the non-woven fabric 210.

Then, the surface-waterproof sheet is dried through a drier 250 andwound in the form of a surface-waterproof paper roll 260.

As described above, the surface-waterproof sheet according to thepresent invention has excellent air permeability and waterproofingproperties. In addition, the surface-waterproof sheet according to thepresent invention secures excellent dimensional stability and cuttingproperties while securing tensile strength. The present invention willbe described in more detail with reference to the following examples andTable 1.

First, the surface-waterproof sheets of the following examples wereprepared by drum coating, and detailed compositions and dryingconditions were as follows.

EXAMPLE 1

On a 0.32 mm thick multi-use non-woven fabric composed of 55 wt % ofcellulose fibers, 40 wt % of glass fibers and 5 wt % of PET fibers andhaving a basis weight of 70 g/m², a waterproof coating solutioncontaining 50 g of a thermosetting acrylic binder (solid content: 45%),50 g of water, 125 g of calcium carbonate (CaCO₃), 3 g of a waterrepellent, 0.3 g of a pigment, and 2 g of an anti-microbial/mold agentwas coated in an amount of 60 g/m², followed by drying at 130° C. for 3minutes.

EXAMPLE 2

The surface-waterproof sheet was prepared in the same manner as inExample 1 except that a 0.44 mm thick multi-use non-woven fabriccomposed of 55 wt % of cellulose fibers, 35 wt % of glass fibers and 10wt % of PET fibers and having a basis weight of 80 g/m² was used.

EXAMPLE 3

The surface-waterproof sheet was prepared in the same manner as inExample 1 except that the waterproof coating solution was coated in anamount of 100 g/m² on the same non-woven fabric as in Example 1.

EXAMPLE 4

Throughout a 0.25 mm thick multi-use non-woven fabric composed of 60 wt% of cellulose fibers, 25 wt % of glass fibers and 15 wt % of PET fibersand having a basis weight of 30 g/m², a waterproof coating solutioncontaining 45 g of a thermosetting acrylic binder (solid content: 45%),50 g of water, 125 g of calcium carbonate (CaCO₃) and 3 g of a waterrepellent was impregnated in an amount of 30 g/m², followed by drying at130° C. for 3 minutes.

Example 5

The surface-waterproof sheet was prepared in the same manner as inExample 4 except that the waterproof coating solution was coated in anamount of 200 g/m² on the surface of the non-woven fabric.

EXAMPLE 6

The surface-waterproof sheet was prepared in the same manner as inExample 1 except that the water repellent was not added to the coatingsolution and was coated on the surface of the non-woven fabric by spraycoating before drying.

COMPARATIVE EXAMPLE 1

The surface-waterproof sheet was prepared in the same manner as inExample 2 except that the waterproof coating solution was impregnatedinto the non-woven fabric instead of being partially permeated into thenon-woven fabric.

COMPARATIVE EXAMPLE 2

The surface-waterproof sheet was prepared using the same non-wovenfabric as in Example 1 and a waterproof coating solution containing 100g of a thermosetting acrylic binder (solid content: 45%), 50 g of water,30 g of calcium carbonate and 10 g of a water repellent was impregnatedthroughout the non-woven fabric.

COMPARATIVE EXAMPLE 3

On a 0 3 mm thick multi-use non-woven fabric composed of 30 wt % ofcellulose fibers and 70 wt % of glass fibers and having a basis weightof 50 g/m², a waterproof coating solution containing 30 g of athermosetting acrylic binder (solid content: 45%), 45 g of water, 200 gof calcium carbonate and 6 g of a water repellent was coated in anamount of 210 g/m² by bar coating, followed by drying at 130° C. for 3minutes.

COMPARATIVE EXAMPLE 4

The surface-waterproof sheet was prepared in the same manner as inComparative Example 3 except that the waterproof coating solution wascoated in an amount of 20 g/m².

COMPARATIVE EXAMPLE 5

On a 0.32 mm thick multi-use non-woven fabric composed of 55 wt % ofcellulose fibers, 40 wt % of glass fibers and 5 wt % of PET fibers andhaving a basis weight of 120 g/m², a waterproof coating solutioncontaining 50 g of a thermosetting acrylic binder (solid content: 45%),50 g of water, 125 g of calcium carbonate (CaCO₃), 3 g of a waterrepellent, 0.3 g of a pigment and 2 g of an anti-microbial/mold agentwas coated in an amount of 60 g/m², followed by drying at 130° C. for 3minutes.

COMPARATIVE EXAMPLE 6

The surface-waterproof sheet was prepared in the same manner as inExample 1 except that the non-woven fabric had a thickness of 0.6 mm

COMPARATIVE EXAMPLE 7

The surface-waterproof sheet was prepared in the same manner as inExample 1 except that the multi-use non-woven fabric was composed of 75wt % of cellulose fibers, 24 wt % of glass fibers, and 1 wt % of PETfibers.

COMPARTIVE EXAMPLE 8

The surface-waterproof sheet was prepared in the same manner as inExample 1 except that, in the multi-use non-woven fabric, the cellulosefibers had an average diameter of 120 μm and an average length of 50 mm,and the glass fibers and PET fibers had an average diameter of 50 μm andan average length of 50 mm

In the above examples and the comparative examples, the basis weight andthe thickness were measured according to KSK ISO 9073-1,2, and the poresize of the waterproof sheet was measured using a capillary flowporometer (Model: CFP-1200 AEIL). Moisture permeability (Cob test) wasmeasured according to KS MISO 535.

Air permeability was measured under a pressure of 196 Pa according toKSK ISO 9073-15. Tensile strength was measured according to KSK ISO9073-18.

Core adhesion was evaluated based on fracture ratio at an interfacebetween a waterproof sheet and a gypsum board when separating asurface-waterproof sheet after preparing the gypsum board using thesurface-waterproof sheet. An area ratio separated from the interface inthe range of 0˜20% was evaluated as high, an area ratio in the range of20˜60% was evaluated as middle, and an area ratio of 60% or moreevaluated as low.

Surface quality was evaluated as high, milled and low according tosurface roughness and whether the glass fibers were exposed. Foldabilitywas evaluated depending on whether the waterproof sheet was efficientlyfolded and cracking occurred at a folded portion when the waterproofsheet was folded.

TABLE 1 Basis Moisture weight of permeability non-woven Coating (g)Tensile fabric Thickness solution Cob 60 Cob 180 Air strength CoreSurface Economic (g/m²) (mm) (g/m²) On Top On Top permeability Dry Wetadhesion quality Foldability feasibility Example 70 0.32 60 8.2 20 1007.8 3.7 High High High High 1 Example 80 0.44 60 7.8 15 150 5.9 2.9 HighHigh High High 2 Example 70 0.32 100 7.9 26 20 7.8 3.6 High High HighHigh 3 Example 30 0.25 30 7 16 100 8.3 4.0 High High High High 4 Example30 0.25 200 8.5 16 130 6.8 3.9 High High High High 5 Example 70 0.32 607.5 120 180 7.8 3.7 High High High High 6 Comparative 80 0.44

8.3 13 150 10.5 4.6 Low Middle Low High Example 1 Comparative 70 0.32

12 18 150 12.7 3.2 Low Middle High High Example 2 Comparative 50 0.30210 — — 0 — — High Low Low High Example 3 Comparative 50 0.30 20 — — 0 —— Middle Low Middle Low Example 4 Comparative 120 0.32 60 9.3 14 14011.3 3.4 Low Middle Low Low Example 5 Comparative 70 0.6 60 8.7 17 16010.8 4.1 Low Low Low Low Example 6 Comparative 70 0.32 60 8.5 18 18012.5 4.2 Low High Middle Low Examplee 7 Comparative 70 0.32 60 8.5 18180 8.6 3.8 Middle Low Low Low Example 8

As described above, in the surface-waterproof sheet for inorganic boardsaccording to the present invention, the waterproof paper body to beadhered to an inorganic board is formed as a single layer of multi-usenon-woven fabrics, and a waterproof coating solution is permeated up to5% to 80% of the non-woven fabric layer from an upper surface of thenon-woven fabric layer to a bottom thereof, thereby providing betterwaterproof properties than existing surface materials while improvingproperties in terms of adhesion to an inorganic board, surface quality,foldability, and economic efficiency.

Further, in the method according to the present invention, the pore sizeand the basis weight of the multi-use non-woven fabrics, and the coatingamount, viscosity and composition of the waterproof coating solution areadjusted, thereby improving dimensional stability and cutting propertieswhile securing strength of the inorganic board.

Although some embodiments have been described, it will be understood bythose skilled in the art that these embodiments are provided forillustration only, and various modifications, changes, alterations andequivalent embodiments can be made without departing from the scope ofthe present invention. Therefore, the scope and spirit of the presentinvention should be defined only by the accompanying claims andequivalents thereof.

1. A surface-waterproof sheet for inorganic boards, comprising amulti-use non-woven fabric comprising cellulose fibers, glass fibers andorganic fibers; and a waterproof coating layer coated on the multi-usenon-woven fabric.
 2. The surface-waterproof sheet according to claim 1,wherein the non-woven fabric comprises 30˜70 wt % of the cellulosefibers, 28˜60 wt % of the glass fibers, and 2˜20 wt % of the organicfibers.
 3. The surface-waterproof sheet according to claim 1, whereinthe cellulose fibers have an average diameter of 5 μm to 100 μm and anaverage length of 1 mm to 30 mm
 4. The surface-waterproof sheetaccording to claim 1, wherein each of the glass fibers and the organicfibers has an average diameter of 5 μm to 20 μm and an average length of1 mm to 30 mm
 5. The surface-waterproof sheet according to claim 1,wherein the multi-use non-woven fabric is formed as a single layer ofthe nonwoven fabric having a basis weight of 30 g/m² to 100 g/m².
 6. Thesurface-waterproof sheet according to claim 1, wherein the multi-usenon-woven fabric has a thickness of 0.25 mm to 0.55 mm
 7. Thesurface-waterproof sheet according to claim 1, wherein the multi-usenon-woven fabric further comprises 0.1˜3 wt % of a dry paperstrengthener or wet paper strengthener.
 8. The surface-waterproof sheetaccording to claim 7, wherein the dry paper strengthener contains starchor polyacrylamide, and the wet paper strengthener contains at least oneselected from among urea formaldehyde resins, melamine formaldehyderesins, polyamide resins, glyoxylated polyacrylamide resins, andpolyethylene imine resins.
 9. The surface-waterproof sheet according toclaim 1, wherein the waterproof coating layer is formed using awaterproof coating solution that comprises 3˜30 wt % of a powderyacrylic binder, 10˜50 wt % of water, 20˜70 wt % of an inorganic filler,0.5˜10 wt % of a water repellent, 0.5˜5 wt % of a pigment, and 0.2˜5 wt% of an antimicrobial agent.
 10. The surface-waterproof sheet accordingto claim 9, wherein the waterproof coating solution has a viscosity of50˜500 cps.
 11. The surface-waterproof sheet according to claim 9,wherein the waterproof coating solution is coated in an amount of 30˜200g/m² on the multi-use non-woven fabric.
 12. The surface-waterproof sheetaccording to claim 9, wherein the inorganic filler comprises calciumcarbonate (CaCO₃) having an average particle size of 5 μm to 50 μm. 13.The surface-waterproof sheet according to claim 9, wherein the waterrepellent comprises a fluorocarbon or wax type water repellent.
 14. Thesurface-waterproof sheet according to claim 1, wherein the waterproofcoating layer is permeated up to 5% to 80% of a thickness of thenon-woven fabric from an upper surface of the non-woven fabric to abottom thereof.
 15. The surface-waterproof sheet according to claim 14,wherein the non-woven fabric has an average pore size of 10 μm to 100 μmin a region into which the waterproof coating layer is not permeated,and an average pore size of 5 μm to 50 μm in a region into which thewaterproof coating layer is permeated.
 16. The surface-waterproof sheetaccording to claim 1, wherein the surface-waterproof sheet has a totalthickness of 0.27 mm to 0.57 mm
 17. The surface-waterproof sheetaccording to claim 1, wherein the inorganic board comprises at least oneselected from among medium density fiberboard (MDF), plywood, cellulosefibers-reinforced cement board, magnesium board, glued laminated timber,high-density fiberboard, ceramic tile, porcelain tile, ceramic board,gypsum board, cement board, and MgO board.
 18. A method of manufacturinga surface-waterproof sheet for inorganic boards, the method comprisingthe steps of: (a) preparing a multi-use non-woven fabric by mixingcellulose fibers, glass fibers and organic fibers; (b) preparing awaterproof coating solution containing a powdery acrylic binder, water,an inorganic filler, a water repellent, a pigment, and an antimicrobialagent; and (c) coating the waterproof coating solution on the multi-usenon-woven fabric, followed by drying the waterproof coating solution.19. The method according to claim 18, wherein the waterproof coatingsolution is coated by one method selected from among drum coating, rollcoating, knife coating, spray coating, and comma coating.
 20. The methodaccording to claim 18, wherein the waterproof coating solution is driedat a temperature of 100° C. to 200° C. for 1 to 10 minutes.